Parallel redundant capacitive sensing device

Abstract

A capacitive detection device includes a set of several detection electrodes for each carrying out capacitive detection at a detection location. Each detection electrode is formed by at least a first measurement electrode and a second measurement electrode. The device also includes first detection electronics forming, with the first measurement electrodes, a first measurement channel, independent from a second measurement channel formed by second detection electronics with the second measurement electrodes. Therefore, for each detection location, the detection device carries out at least two redundant and independent detection operations.

Claims

1. A device for capacitive detection of an object, comprising: a set of capacitive detection electrodes each carrying out a capacitive detection for a detection location of a detection surface, each detection electrode comprising at least one first and one second independent electrodes, called measurement electrodes, said also comprising: first detection electronics for the first measurement electrodes of said assembly, forming with said first measurement electrodes a first detection channel, to polarize said first measurement electrodes at an alternating potential, called excitation potential, different from a ground potential, and measure a signal relative to a capacitance, called electrode-object capacitance, between each first measurement electrode and said object; and second detection electronics for the second measurement electrodes of said assembly, forming with said second measurement electrodes a second detection channel, to polarize said second measurement electrodes at said excitation potential and measure a signal relative to an electrode-object capacitance between each second measurement electrode and said object.

2. The device according to claim 1, characterized in that, for at least one detection electrode, the first and second measurement electrodes are juxtaposed in a non-interleaved manner.

3. The device according to claim 1, characterized in that, for at least one detection electrode: one of the first and second measurement electrodes is at least partially interleaved with the other of said measurement electrodes; or the first and second measurement electrodes are at least partially interleaved with one another.

4. The device according to claim 1, characterized in that it also comprises at least one guard electrode for at least a first, respectively second measurement electrode, polarized at an alternating guard potential identical or substantially identical to the excitation potential at least one working frequency.

5. The device according to claim 4, characterized in that at least one guard electrode: is common to all the measurement electrodes forming a detection electrode; and/or is common to several first, respectively second measurement electrodes, and/or forms a guard plane common to several, in particular all, the detection electrodes.

6. The device according to claim 1, characterized in that the detection electronics of each detection channel comprises a measurement module supplying a detection signal relative to one or more capacitances, called electrode-object capacitances, between one or more measurement electrodes of said detection channel and one or more objects in proximity to, or in contact with, said measurement electrode or electrodes.

7. The device according to claim 1, characterized in that it also comprises a control module arranged to compare signals measured respectively by the first detection electronics and the second detection electronics.

8. The device according to claim 1, characterized in that at least one of said first and second detection channels comprises a polling means to poll at least a part of the measurement electrodes of said detection channel sequentially.

9. The device according to claim 1, characterized in that the detection electronics of each detection channel is at least partially electrically referenced to the alternating excitation potential.

10. The device according to claim 1, characterized in that it comprises an oscillator supplying the alternating excitation potential for the first and second detection channel, and the guard potential (V.sub.G) if required.

11. A detection layer, for an item of equipment, fitted with a detection device according claim 1.

12. The detection layer according to claim 11, characterized in that it comprises, along a face, a plurality of detection electrodes distributed according to a matrix arrangement, each of said detection electrodes comprising at least a first and a second measurement electrodes juxtaposed and/or interleaved.

13. The detection layer according to claim 11, characterized in that it comprises, along a face, at least one detection electrode, and along another face, at least one guard electrode.

14. The detection layer according to claim 11, characterized in that it has the form of a rigid or resilient trim element.

15. An item of equipment fitted with a detection layer according to claim 11.

16. An item of equipment fitted with a detection device according to claim 1.

17. The item of equipment according to claim 16, characterized in that it is a robot, a robotized handling arm or a robot segment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Other advantages and characteristics will become apparent on examination of the detailed description of non-limitative examples and from the attached drawings in which:

(2) FIG. 1 is a diagrammatic representation of a non-limitative embodiment of capacitive detection electronics that can be utilized in the device according to the invention;

(3) FIG. 2 is a diagrammatic representation of a non-limitative embodiment example of a detection device according to the invention;

(4) FIGS. 3-7 are diagrammatic representations of non-limitative embodiment examples of a detection electrode that can be used in a detection device according to the invention; and

(5) FIG. 8 is a diagrammatic representation of a non-limitative embodiment example of a robot equipped with a detection device according to the invention.

DETAILED DESCRIPTION

(6) It is well understood that the embodiments that will be described hereinafter are in no way limitative. Variants of the invention can in particular be envisaged comprising only a selection of characteristics described hereinafter in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art. This selection comprises at least one, preferably functional, characteristic without structural details, or with only a part of the structural details if this part alone is sufficient to confer a technical advantage or to differentiate the invention with respect to the state of the prior art.

(7) In particular, all the variants and all the embodiments described can be combined together if there is no objection to this combination from a technical point of view.

(8) In the figures, elements that are common to several figures retain the same reference.

(9) FIG. 1 is a diagrammatic representation of a non-limitative embodiment of capacitive detection electronics that can be utilized in the device according to the invention.

(10) The detection electronics 100, shown in FIG. 1, can be produced in an analogue or digital form, or an analogue/digital combination.

(11) The detection electronics 100 receives an alternating excitation voltage, denoted V.sub.G, from an oscillator 102, referenced to a ground potential 104.

(12) The voltage V.sub.G is used as guard potential in order to polarize one or more guard electrodes via a line or several lines 106, and as excitation potential in order to polarize “n” measurement electrodes via “n” lines 108.sub.1-108.sub.n, where n≥1.

(13) The detection electronics 100 comprises a current, or charge, amplifier 110 represented by an operational amplifier (OA) 112 and a feedback capacitor 114 looping the output of the OA 112 to the “−” input of the OA 112.

(14) In addition, in the example shown, the “+” input of the OA 112 receives the voltage V.sub.G and the “−” input of the OA 112 is provided in order to be connected to each detection electrode via a polling means 116, which can be for example a switch, so as to poll a set of “n” measurement electrodes individually in turn. The lines 108.sub.1-108.sub.n are all connected to the polling means 116.

(15) Under these conditions, the charge amplifier 110, and in particular the OA 112, supplies at the output a voltage V.sub.s at an amplitude proportional to the coupling capacitance C.sub.eo, called electrode-object capacitance, between the measurement electrode connected to the “−” input thereof and an object in proximity, or in contact, with said measurement electrode.

(16) The detection electronics 100 can also comprise a signal conditioner 118 making it possible to obtain a signal representative of the sought coupling capacitance C.sub.eo. This signal conditioner 118 can comprise, for example, a synchronous demodulator for demodulating the signal with respect to a carrier wave, at a working frequency. The signal conditioner 118 can also comprise an asynchronous demodulator or an amplitude detector. This signal conditioner 118 can of course be produced in an analogue and/or digital form (microprocessor), and comprise all necessary means for filtering, conversion, processing etc.

(17) The signal conditioner 118 measures and supplies the value of the voltage V.sub.S.

(18) The current or charge amplifier 110 and the signal conditioner 118 thus constitute a measurement module which supplies a signal relative to the electrode-object coupling capacitance C.sub.eo.

(19) The detection electronics 100 also comprises a calculation module 120 arranged in order to determine a distance or an item of distance information, and/or a contact or an item of contact information, between the measurement electrode and the object, as a function of the signal with respect to the coupling capacitance C.sub.eo originating from the signal conditioner 118.

(20) This calculation module 120 can for example comprise or be produced in the form of a microcontroller, or an FPGA.

(21) The calculation module can also supply other items of information, such as triggering of alarms or safety procedures, when for example the measured distances are below the predetermined distance thresholds.

(22) Of course, the measurement electronics 100 can comprise components other than those described.

(23) The detection electronics 100, or at least its sensitive part with the charge amplifier 110, can be referenced (or supplied by electrical power supplies referenced) to the guard potential V.sub.G, in order to minimize the parasitic capacitances.

(24) The detection electronics 100 can also be referenced, more conventionally, to the ground potential 104.

(25) The detection electronics supplies at an output 122 a signal relative to the capacitance C.sub.eo, or to the distance between the object and the measurement electrode.

(26) FIG. 2 is a diagrammatic representation of a non-limitative embodiment example of a redundant capacitive detection device according to the invention.

(27) The detection device 200, shown in FIG. 2, comprises an assembly of several detection electrodes 202.sub.1-202.sub.n. The detection electrodes 202.sub.1-202.sub.n are shown along a line for the sake of clarity. Of course, the detection electrodes 202.sub.1-202.sub.n can be placed in the form of a matrix, for example of detection electrodes 202.sub.1-202.sub.n in a square or diamond shape, or according to any configuration other than that shown in FIG. 2.

(28) The detection electrodes 202.sub.1-202.sub.n are each associated with a detection location, or pixel, on a detection surface.

(29) Each detection electrode 202.sub.i is formed by two measurement electrodes: a first measurement electrode 204.sub.i and a second measurement electrode 206.sub.i. The two measurement electrodes 204.sub.i and 206.sub.i, forming a detection electrode 202.sub.i, are independent of one another, and are used to carry out a double detection at one and the same detection location/pixel, namely the location associated with the detection electrode 206.sub.i. To this end, a signal relative to the electrode-object capacitance is measured independently for each measurement electrode 204.sub.i and 206.sub.i, for example according to the principle described with reference to FIG. 1.

(30) The detection device 200 also comprises first detection electronics 1001 associated with all the first measurement electrodes 204.sub.1-204.sub.n of all the detection electrodes 202.sub.1-202.sub.i.

(31) The first detection electronics 100.sub.1 forms with the first measurement electrodes 204.sub.1-204.sub.n a first detection channel.

(32) The first detection electronics 100.sub.1 can be identical to, or operate on the principle of, the detection electronics 100 in FIG. 1.

(33) The first detection electronics 100.sub.1 is connected to all the first measurement electrodes 204.sub.1-204.sub.n by virtue of the lines 108.sub.1.sup.1-108.sup.1.sub.n. The first measurement electronics supplies at its outlet 122.sub.1 a detection signal relative to the electrode-object capacitance C.sub.eo, or to the electrode-object distance, for each of the first measurement electrodes 204.sub.1-204.sub.n.

(34) The detection device 200 also comprises second detection electronics 100.sub.2 associated with all the second measurement electrodes 206.sub.1-206.sub.n of all the detection electrodes 202.sub.1-202.sub.n.

(35) The second detection electronics 100.sub.2 forms with the second measurement electrodes 206.sub.1-206.sub.n a second detection channel, independent of the first detection channel.

(36) The second detection electronics 100.sub.2 can be identical to, or operate on the principle of, the detection electronics 100 in FIG. 1.

(37) The second detection electronics 100.sub.2 is connected to all the second measurement electrodes 206.sub.1-206.sub.n by virtue of the lines 108.sub.1.sup.2-108.sup.2.sub.n. The second measurement electronics supplies at its outlet 122.sub.2 a detection signal relative to the electrode-object capacitance C.sub.eo, or to the electrode-object distance, for each of the second measurement electrodes 206.sub.1-206.sub.n.

(38) Thus, each of the first and second detection channels supplies a measurement, and a detection, which is independent for each detection location. As a result, the device 200 ensures a redundant capacitive detection for each detection location.

(39) The detection device 200 also comprises a control device 210 one of the functions of which is to verify the correct operation of the assembly and to detect failures of one or the other detection channels.

(40) In the embodiment mode shown, this control module 210 comprises two control sub-modules, 210.sub.1 and 210.sub.2, implemented respectively in the calculation modules 120 of the first and second detection channels. The control sub-modules 210.sub.1, 210.sub.2 are arranged to compare measurement signals originating from their respective detection channel with those originating from the other detection channel.

(41) The control module 210 can thus determine differences between the measurement signals originating respectively from the first and the second detection channel, which reveal failures of at least one of the detection channels. In the case of a difference of measurement between the channels above a predetermined threshold, the control module 210 can trigger safety procedures, such as for example slowing or stopping of the system. This triggering can be carried out via calculation modules 120, or by outputs that are part of the control module. It should be noted that a safety procedure can thus be triggered as soon as a difference is detected between the channels, without seeking to determine which of the channels is faulty.

(42) According to an advantageous aspect of the invention, the detection channels can be used simultaneously, in a synchronous or asynchronous manner, as they do not interfere with one another. In particular, a synchronous use makes it possible to obtain two measurements simultaneously under identical conditions and thus to detect failures more quickly and effectively.

(43) Of course, the measurement channels can also be used sequentially or in turn. In this latter case, a communication line can be provided between the detection channels to ensure a detection in turn.

(44) The device 200 also comprises a guard electrode 208, forming a common guard plane for all of the detection electrodes 202.sub.1-202.sub.n, and thus for all of the first and second measurement electrodes.

(45) The guard electrode 208 is polarized at the guard potential V.sub.G, for example via the line 106, as described with reference to FIG. 1.

(46) Alternatively, the detection device according to the invention can utilize a guard electrode that is: individual for each measurement electrode within a detection electrode, or common to the measurement electrodes of one and the same detection electrode; or common to several, or to all, of the first measurement electrodes, or also common to several, or to all, of the second measurement electrodes.

(47) In FIG. 2, non-limitatively, each detection electrode 202.sub.i is formed by two measurement electrodes.

(48) Of course, according to a general formula, each detection electrode 202i can be formed by “k” measurement electrodes, with k≥2. In this case, the redundant capacitive detection device according to the invention can comprise “k” independent detection electronics 100.sub.1-100.sub.k, each associated with one of the measurement electrodes of each detection electrode 202.sub.i.

(49) In addition, in FIG. 2, each detection electrode 202.sub.i is formed by two juxtaposed measurement electrodes in the shape of a triangle. If course, the shape and the arrangement of the measurement electrodes of a detection electrode are not limited to this example.

(50) FIG. 3 gives an embodiment example of a detection electrode that can be implemented in a redundant capacitive detection device according to the invention.

(51) In the example described in FIG. 3, the detection electrode 202 is formed by a first measurement electrode 204, entirely interleaved with a second measurement electrode 206. The second measurement electrode 206 completely surrounds the first measurement electrode 204. The connection tracks can then be produced on another layer of conductor.

(52) FIG. 4 gives an embodiment example of a detection electrode that can be implemented in a redundant capacitive detection device according to the invention.

(53) In the example described in FIG. 4, the detection electrode 202 is formed by a first measurement electrode 204, entirely interleaved with a second measurement electrode 206. The second measurement electrode 206 does not completely surround the first measurement electrode and has the shape of a “C”.

(54) FIG. 5 gives an embodiment example of a detection electrode that can be implemented in a redundant capacitive detection device according to the invention.

(55) In the example described in FIG. 5, the detection electrode 202 is formed by a first measurement electrode 204, and a second measurement electrode 206 which are interleaved with one another. Each measurement electrode has the shape of a comb. The combs are interleaved with one another.

(56) FIG. 6 gives an embodiment example of a detection electrode that can be implemented in a redundant capacitive detection device according to the invention.

(57) In the example described in FIG. 6, the detection electrode 202 is formed by four measurement electrodes 204, 206, 602 and 604 which are interleaved with one another in threes. The measurement electrodes 204 and 206 are identical and face one another. The measurement electrodes 602 and 604 are identical and face one another.

(58) Each measurement electrode is interleaved with the two measurement electrodes which are juxtaposed to it.

(59) FIG. 7 gives an embodiment example of a detection electrode that can be implemented in a redundant capacitive detection device according to the invention.

(60) In the example described in FIG. 7, the detection electrode 202 is formed by a first measurement electrode 204, juxtaposed with a second measurement electrode 206.

(61) As above, the examples of detection electrodes described in FIG. 3 to FIG. 7 can be arranged to cover a detection surface according to matrix, radial etc. arrangements.

(62) FIG. 8 is a diagrammatic representation of a robot equipped with trim elements according to the invention.

(63) The robot 800 shown in FIG. 8, is a robotized arm comprising several segments that are articulated and connected to one another by rotary articulations.

(64) The robot 800 comprises two trim elements 802 and 804 placed on two segments of the robot 800.

(65) Each trim element 802-804 comprises a detection device according to the invention, such as for example the detection device 200 in FIG. 2.

(66) The detection electronics of the detection devices equipping the trim elements 802 and 804 can be separate, or partially or completely common.

(67) The detection electrodes 202 of each detection device equipping the trim elements 802-804 are integrated in the thickness of said trim element, or arranged on a face or the faces of said trim element 802-804.

(68) The trim elements 802-804 also comprise a guard layer to avoid parasitic couplings between the electrodes and the structure of the robot.

(69) The trim elements 802-804 are used either in place of an original trim element of the robot, or in addition to an original trim element.

(70) Of course, the invention is not limited to the examples that have just been described, and numerous modifications may be made to these examples without exceeding the scope of the invention.